Last year, I went on a guided tour, and one of the first things that the ARTery guide said was that we could download the mp3 for the tour every year...
So here I am, trying to get ready, and to download the mp3 for this year, but I can't find it! :(

It's back-masked into last year's audio tour. What you're basically gonna wanna do is get a vinyl record pressed of the '07 audio tour, and bring it along with a record player. As you wander along in the desert, wind the record backwards with your finger. The old-style Victrolas work great for this, with their built in speaker... you're just going to need to prepare your arms for their awkward girth and immense weight. And keep the record out of direct sunlight.